Degradation of amoxicillin under a UV or visible light photocatalytic treatment process using Fe2O3/bentonite/TiO2: Performance, kinetic, degradation pathway, energy consumption, and toxicology studies

Abstract

The present work investigates the degradation of amoxicillin (AMX) using a Fe2O3/bentonite/TiO2 (Fe2O3/B/TiO2) nanocomposite under visible LED light and UV irradiation. XRD, UV-Visible, FTIR, EDS, VSM, EPR spectra and TEM techniques were utilized to estimate the features of the prepared photocatalyst. The saturation magnetization for Fe2O3 and Fe2O3/B/TiO2 was 57.4 and 17.4 emu/g, respectively. Factors affecting degradation rates, such as pH, catalyst dose, radiation intensity, and initial AMX concentration, were investigated. The results showed that an AMX concentration of 25 mg/L, a pH of 5, and a catalyst dosage of 0.75 gr/L are the optimal parameters suggesting a 100% degradation of the contaminant in the presence of UV light for 60 min. However, during the use of visible light the optimal contact time was 90 min, producing a removal percentage of 98.8%. The results for the reaction rate indicate the adherence of the data to pseudo-first-order kinetics, and the reaction rate constant for UV and visible radiation was 0.0181 and 0.0176 1/min, respectively. The energy consumption range for a degradation time of 10–90 min for UV and visible radiation was 9.4–14.6 and 7.61–15.4 kWh/m3, respectively Both light sources have also been shown to convert nonbiodegradable effluent into a biodegradable form. Finally, a mere 8% reduction in catalyst efficiency was observed after 6 recycling and reuse cycles. The degradation of AMX was negatively affected by common coexisting anions in water (10–25%). Moreover, toxicity assessments indicated the usability of the studied system to remarkably diminish the toxicity of AMX solution compared to untreated controls. Hence, the studied Fe2O3/B/TiO2/UV or visible light processes could be considered an auspicious technology for providing high efficiencies in the treatment of AMX-contaminated wastewater.